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by sorkin2 3359 days ago
> Changing from master to replica is easy, but now you have to rebuild that original master off of the former replica now. Completely start over. You can't just start up again from a given transaction ID. MySQL's GTID implementation is much better in this regard. You can change masters and replicas all repoint them without rebuilding. You can't do that (currently) with Postgresql.

Have you heard of pg_rewind? https://www.postgresql.org/docs/current/static/app-pgrewind....
1 comments
scurvy 3358 days ago
I had not. Looks like it requires 9.5 or later? We're running 9.4 so we'll have to upgrade to use it. Thanks!
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mb4nck 3358 days ago
You can get pg_rewind for 9.4 (and 9.3 in its branch) here:

https://github.com/vmware/pg_rewind/tree/REL9_4_STABLE

It's from the people who wrote it upstream, they provide the code there for earlier Postgres releases.

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scurvy 3347 days ago
Does this help at all with upgrades? Upgrading from 9.4 to 9.5 means you need to rebuild your entire replication topology because the master's identifier has changed (in the initdb step of the official docs).
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